Method of producing heat exchange elements



I Oct. 27, 1953 J. PLUMERI ETAL 2,656,808

METHOD OF PRODUCING HEAT EXCHANGE ELEMENTS Filed March '7, 1947 Patented Oct. 27, 1953 METHOD F PRODUCING'HEAT EXCHANGE ELEMENTS Arpad L. Reisinger; Trenton,

N; J., a'ssi'gnors to Kramer Trenton Company, Trenton, N. Jr, acorporation of New Jersey ApplicationMarch 7, 1947; SeriaLNoi 7 33 020 4' Claims; I.

This invention relates to method of producing a" heat exhange element, and more particularlya which is adapted to be asshci'ated with a tubular conduit in the manufacture "or heat exchange apparatus such, for instance, as evaporators, radiators and the like. i V

An object of the invention is to provide such an element which embodies improved means for spacing. it from adjacent fins when arranged on a conduit; especially when a substantial amount of. spacing is desired as for instance, when air circulation through the apparatus is caused by natural forces as distinguished from the effect of a fan or analogous means.

Another object is to provide such an element in which the spacing means is formed concurrently with the formation of the aperture ior receiving the conduit or tube and inwhich the eifectivelength or lateral. projection of the spacing means from the fin is greater than one-half the diameter of the aperture Another object is toprovide such an element] in which the portion of the fin intended-tor the formation oi the conduit or tube receiving aperture is bothdrawn andipunched to form the aperture with fin spacing projections at its periphery which are greater in the extent of their lateral projectionifrom the finthan one-half the diameter of theap erture. V

Another object is to provide such an element in whichthe portion of the fin intended for the formation of the conduit or tube receiving apertureis punched out eccentrically in order to form the aperture with projections at its periph cry, a portion of which projections are greater in lateral extent than one-half the diameter of the aperture.

Another object is to provide such an element having fin spacing projections extending laterally, from the periphery of its conduit or tube receiving. aperture a distance greater than oneh'alf the diameter of the aperture, which element is adapted for facile and speedy association in groups with a tube or conduit, and for fixation in position on the latter either by expanding the conduit or tube,;or by constricting the said pro- .ifibti'ons- Another object is to provide a method oi-produci 'ng such an element in'vvhi'ch the area of thefiriwhere the conduit or tube receiving aperture is to be formed ispreliininarily increased, as by drawing the metal, so that,.when thelmaterial is punehediout to form the aperture, spacing proj'ections; are simultaneously formed at the pe: riphery of the aperture, the lateral} extent ot the projections being greater than one-half the diameter of theaperture;

Another object isto provide a method of producing such an element in which the portion 01' the material where the conduit or tube receiving aperture is' to be formed, is preliminarily drawn by a progressive cuppingprocedure in which the cup formationis gradually increased in depth :and'decreased-in width or diameter.

Another object is to provide a method of pro'e ducing suchan element inwhich the portion; of the material where the conduit Or tube receiving aperture is to be formed, is punchedouteccentrically so as to provide fin spacing projections at the periphery of the aperture which vary in the extent of their lateral projection and some of which extend laterally a distance greater-than one-half the diameter of the aperture.

A further object is to provide certain provements in the form, construction, and arrangement oi the parts and in the stepsof the method, of producing the element; whereby the above named and other objects may be efiectively attained.

Practical: embo meritsof the invention are represented in the accompanying drawings in which: i

Fig. 1: represents a detail portion of; tube with several erative position thereon;

, Fig. 2 represents abroken section taken the plane. ofthe 1ineIIII- of Fig. 1, looking in the di-rectionofthe arrows;

Figt3 represents avertical section taken-mi the planegof the line IIIII-I of Fig. 2, looking in the direction of the arrows;

Fig. 4 represents a brckenplan view of a fin, looking in the direction-opposite to'Fig. 2;

Fig 5- represents anedge View ofa-fin;

Fig. 6 represents a: detail plan-view,ona larger scale,- of the first stageoi the drawing or cupping operation inthe manufacture of a fin;

7 represents the next stage of the" said operation;

Fig.6 represents-the third'stage;

Fig. 9 represents the fourth stage inwhich; the punching tool has scored the bottom of; the cupped portiono-f thefin;

Fig. 10 represents the fifth stage in which: the

sideelevation of a fins arranged in oppunchingstep has beencompleted;

Figs, 1 1', 12' 1:3,1 i and 15 represent vertical sections; taken respectively, onthe lines XIl XII; XII I -XIII and of Figs, 6, 7, 8 9 and 10, looking in-the directionof the arrows; I

Fig. 16 represents-a viewsimilar to 9; but showing score lines formed by" aneccentric punch;

Fig, 1;?" represents a, vertical section" taken; lit the plane of the line-XVIP -XVIL of Fiignl'fiplookw ing in the direction of the arrows; and

Fig. 18 represents a similar view following the completion of the action of the eccentric punch.

In the manufacture of heat exchange apparatus which embodies tubes with fins thereon,

. proper spacing of the fins is a matter of notable importance and efforts have been expended for many years looking to the betterment of this feature. As expedition and economy in production of fins are essential to successful commercial opstamped or punched therefrom in the same operation which forms the tube receiving aperture;

the said projections being spaced from the aperture. This procedure has given rise to objections relating chiefly to difficulty in assembly and lack of uniformity in the arrangement of the assembled fins on the tube. For instance, where the size of the fins has been comparatively large in relation to the cross sectional size of the tube and the sheet material of which the fin is formed is quite thin, any slight irregularity in the circular form of the tube or any slight distortion of the plane of the fins tends to cause binding when the elements are assembled, irregularity in the form and arrangement of the fins and imperfect thermal contact between the fins and the tube. These and other difficulties have been largely overcome by forming the spacing projections at the edge or circumference of the tube receiving aperture in the fins, but this expedient has had its own'drawback or limitation because the spacing projections formed at the time the aperture is punched in the fin have been limited in the extent of their projection laterally from the fin to a measurement equal to one-half the diameter of the aperture. This is because the material constituting'the projections is the material punched from the fin when the aperture is formed. Hence,

. to illustrate, if heat exchange apparatus is designed for a three-eighths inch diameter tube,

the spacing projections formed as just described will be only three-sixteenths of an inch in length, so that the spacing of the fins when assembled on the tube cannot be greater than three-sixteenths of an inch. However, there are many occasions, particularly when the apparatusis to be used in connection with gravity circulation of air, as

distinguished from forced circulation by fan, or the like, when a greaterspacing of the fins is highly desirable, if not essential. This invention provides for the manufacture of fins having spacing projections located at the edge of circumference of the fin aperture, 'whichprojections are embodying this invention,

4 than the external circumference of the tube I, in order that the fin may be assembled on the tube in spaced arrangement with other fins, as well shown in Figs. 1 and 3.

From the edge or circumference of the aperture 3 a plurality, of spacing projections 4 extend laterally with respect to the fin sothat, when the parts are assembled as illustrated in Figs. 1 and 3, the projections 4 will uniformly space the fins from each other. It is preferred to curl or bend the extremities of the projections 4, as indicated at 5, in order to increase the smoothness, firmness, and extent of their contact with adjacent fins. The area of the fin intermediate the aperture 3 and the outer periphery of the fin is dished or offset, as denoted at 6, to increase the strength and rigidity ofthe fin as a whole; and a small tip or projection I is provided to serve as a guide to the operative when arranging and aligning the fins in groups tube, as is well understood by those familiar with the production of heat exchange apparatus of this general type.

In the manufacture or production of apparatus the tube or conduit 1 may be drawn or otherwise produced in any well known or approved manner. The fins, however, are produced according to a novel method which constitutes part of this invention. In this operation, sheet material, such as copper, brass or aluminum, is provided, and is subjected, in a die press, or the like, to a series of progressive operations which form cups or depressions in the sheet metal which gradually increase in depth and decrease in diameter, as is well illustrated in Figs. 6 to 9 inclusive and 11 to 14 inclusive where the cup formations are denoted respectively by 8, 9, l0, and il. As machines and tools for drying or pressing operations of this character are well known to those versed in the metal working art, it is deemed unnecessary here to provide any illustration or description thereof. After the metal has been distorted into the cup form represented inFigs. 9 and 14, the bottom of the cup is punched through, by a rip punch, or the like, in order to forma series of the hereinbefore mentionedprojections 4 extending laterally from the edge or circumference of the aperture 3; whereupon, if desired, an appropriate die or other tool may be brought into contact with the extremities of the projections 4 in order to impart to them the bend or curved formations 5. The score lines formed by the rip punch at the outset of its acgreaterin length or lateral extension from the fin than one-half diameter of the aperture; whereby the heretofore existing difficulties or drawbacks are eliminated and a greatly improved product is obtained.

With reference to the form of the invention shown in Figs. 1 to 15 inclusive, a tube or conduit is denoted by I and is preferably composed of a suitable heat conducting metal such, for instance,

' as'coppen-brass or aluminum; the cross section of the tube being shown as circular, which is customary in this art. One of the fins, of which a considerable number are commonly assembled on the tube,is marked 2, and it is preferably composed of thin sheet metal such as one of those just'mentioned. In the present instance the fin is illustrated as being substantially square, and it is provided with a central aperture3 which is circular in form and slightly greater in size tuation are shown in Fig. 9 and marked l2,'which lines determinethe general shape of the projections i. H r

itwill be observed that each of the projections 4 extends laterally from the fin a distance somewhat greater than one-half the diameter of the aperture 3 which enables adjacent fins to, be spacedby the said'projections a greater distance apart than would be the fact if the fin material had not been subjected tothe cup drawing operations prior to the action of the rip punch in forming the aperture 3 and the projections. In other words, each. projection 4 embodiesin its lateral extent from the fin, not only, one-half the diameter of'the bottom of thecup i I, but also the depth or the side of the cup, so that, strictly speaking, the side of the cup constitutes a collar or flange protruding laterally from the periphery of the aperture 3, while the projections 4 extend laterallyin, the samedirection from'the side of the cup; the bases of the projections being contiguous along the line at which they unite with for assembly with the the side of the cup and the said projections tapering toward their extremities. When the extremities of the projections 4 are bent or curled, as indicated at 5, the effective length of the projections is, of course, lessened but, even so, the effective length of the projections remains greater than it would have been if the original length of the projections had not been increased by the cup drawing operations. Furthermore, it is not necessary to bend or curl the extremities of the projections as they may be used at full length, and, finally, the extent to which the effective length of the projections is reduced by the bending or curling of their extremities may be varied by the amount of the bend or curl.

Turning to the form of the invention represented in Figs. 16, 17 and 18, the fin structure and the method by which it is produced are the same as hereinabove set forth, the change or modification residing in the fact that an eccentric rip punch, or analogous tool, is used for the step of punching out the bottom of the cup, here marked it, to form the tube receiving aperture, here marked 14, and the spacing projections, here marked I5, I 6, I l and I8. The score lines shown in Fig. 16 and marked collectively 19 indicate the eccentricity of the rip punch, or the like, and it will be observed from them, as well as from Fig. 18, that the eccentricity of the tool causes certain of the spacing projections to be longer than the others, i. e. projection I8 is longer than I 7 and I1 is longer than IS. The eccentricity of the punching tool will make at least one of the projections greater in length than onehalf the diameter of the aperture I4 and will thus further increase the effective length of the said projection. It will be clear that, by changing the design of the cutting face of the tool, the number of projections formed thereby and the relative length of the said projections can be varied at will. It should be added that the extremities of the projections formed in this embodiment of the invention may also, if desired, be bent or curled as shown and described in connection with the other form of the invention.

Though this modified form of the invention magnifies the spacing function of the projections, it may not be, under certain conditions, as desirable as the previously described form of the invention because the spacing effect is obtained by only some of the projections and, furthermore, the spacing contact of adjacent fins does not extend around the whole circumference of the tube receiving aperture. While, in this modified form of the invention shown in Figs. 16, 17 and 18, the fin material is subjected to the cup drawing operations before the action of the rip punch, it is not essential that this procedure be followed, since the eccentric tool would cause one or more of the projections to be greater in length than one-half the aperture even if the tool were caused to act; upon fiat sheet material.

With reference to both forms of the invention, it will be evident that the hereinbefore mentioned advantages are attained to a high degree and the hereinbefore mentioned drawbacks correspondingly eliminated, while the operating procedure does not require the use of machine devices of types other than such as are, and have been, employed in the stamping out or die pressing of previously known forms of fins, except as respects the eccentric cutting face of the rip punch used in connection with the form of the invention illustrated in Figs. 16, 17 and 18. The manufacturing steps are simple and may be performed with great rapidity by automatic machines, and the fins may be handled in the usual stacking magazines in the same manner as previously known fins which lack the novel features of this invention. Finally, after the fins have been assembled on the tube or conduit, they may be fixed in position by either expanding the tube or constricting the spacing projections.

It will be understood that various changes may be resorted to in the form, construction, arrangement and material of the parts, and in the steps of the method of production, without departing from the spirit and scope of the invention; and hence we do not intend to be limited to details herein shown and described except as they may be included in the claims or required by disclosures of the prior art.

What we claim is:

1. A method of producing a circularly apertured heat exchange fin designed and adapted for assembly in thermal contact and in substantially uniformly spaced relationship with respect to other similar fins on a round tube of heat exchange apparatus which includes the following steps: providing sheet material suitable for the formation of such a fin; drawing a portion of said material into cup form having a diameter greater than the designed final diameter of the fin aperture; progressively increasing the depth and decreasing the diameter of the said cup portion until its diameter equals the said designed final diameter; and without any previous cutting or scoring operation forming with a single punching operation within the cup and through its bottom a tube receiving aperture of the same diameter as the cup, and a thermal contact and fin spacing element having a lateral extent greater than one-half the diameter of said aperture and consisting of a flange composed of the side of the cup and surrounding the aperture with lateral projection composed of the bottom of the cup extending from the peripheral edge of the flange in substantially the same direction as the flange.

2. A method as defined in claim 1, in which the whole bottom of the cup is used for forming the projections.

3. A method as defined in claim 2, in which the punching operation is eccentric with relation to the cup bottom.

4. A method as defined in claim 1, which also includes the step of turning the extremities of the projections outwardly.

JOHN PLUMERI. ARPAD L. REISINGER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 183,878 Young Oct. 31, 1876 689,394 Gregory Dec. 24, 1901 1,591,323 Karmaz'in July 6, 1926 1,724,486 Karmazin Aug. 13, 1929 1,775,706 Trane Sept. 16, 1930 1,997,563 Karmazin Apr. 9, 1935 1,998,664 Erbach Apr. 23, 1935 2,004,182 Arey June 11, 1935 2,012,269 Cornell Aug. 27, 1935 2,046,791 Przyborowski July 7, 1936 2,089,340 Cobb Aug. 1.0, 1937 FOREIGN PATENTS Number Country Date 537,480 France May 24, 1922 321,820 Great Britain Nov. 21, 1929 

